Abstract: The apparatus according to this invention is provided with a stack assembly composed of two kinds of cells disposed in such order of arrangement that the adjacent cells are different in kind from each other. A first cell includes a first fluid distribution means and a membrane lying on either side of said means. A second cell includes a second fluid distribution member that forms independent tunnel-like fluid paths between the membrane support sheet and respective ones of the paired members having a plurality of grooves on one surface thereof, said membrane support sheet being provided with a large number of projections on the central portion thereof and said pair of grooved members being arranged so that the grooved surfaces are face-to-face with each other, interposing said membrane support sheet therebetween.

Abstract: A small-sized plate type fluid treatment apparatus for filtration and separation of fluid, transferring substances between fluids through membranes or passing specific substances contained in the fluid through membranes. Said apparatus consists of a plurality of stacked membrane arrangements which comprises membrane support-plates, each being molded in thickness of 1.2 mm or less by means of embossing or press work, and a single membrane interposed between said membrane support-plates. The membrane support-plate composing the membrane arrangements of this apparatus is so designed that the 1st fluid is fed into the space defined by the 1st membrane support-plate and the membrane, and the 2nd fluid is fed into the space defined by the 2nd membrane support-plate and the foresaid membrane, with no abruptly narrowed passage for fluid. Therefore, even when as thin a membrane support-plate as 1.2 mm or less in thickness is used, residence of bubbles is prevented in the fluid in the performance of the apparatus.