Abstract: A permeation separation apparatus furnished with an assembly consisting essentially of a multiplicity of continuously hollow fibers which have a selective permeability to fluid, said hollow fibers being arranged on the surface of a core so as to constitute multiple layers of the hollow fiber lines wherein the hollow fiber lines are disposed in mutually and up- and downwardly intersecting relations and are crossed two or more layers, said each layer having a thickness equal to the diameter of a piece of hollow fiber, with a resin wall or resin walls provided at one terminal or at both terminals of said hollow fiber layers, each of said hollow fiber lines thrusting through at least one of said resin walls in a fluid-sealing condition to provide an opening outward, and said hollow fiber being disposed so as to satisfy the formula:.pi.D/10L.ltoreq.tan B.ltoreq.3.pi.

Abstract: A large-sized hollow fiber membrane separation apparatus suitable for treating a large amount of fluid without any defect, such as pressure loss of fluid, a concentration polarization phenomenon and the like, which comprises a cylindrical pressure container divided into two longitudinally aligning compartments by a dividing member at the substantial longitudinal center portion thereof; two columnar hollow fiber assemblies longitudinally aligned and placed in the compartments, respectively; said dividing member having functions to seal the compartments in a fluid-sealing condition, to feed fluid to be treated and to discharge fluid which does not permeate through the hollow fiber membrane during membrane separation in the compartments and being directly connected to external pipings through opening provided to the side wall of the container at the substantial longitudinal center portion thereof.